Impression cytology in patients with keratoconjunctivitis sicca.

Impression cytology is a simple and painless procedure that allows the collection of the superficial layers of the conjunctival epithelium. Each sample is assigned a grade of epithelial metaplasia, and goblet cell density is calculated in each one. We have studied the superior and temporal bulbar conjunctiva of dry eyes and have compared it with that of normal controls. In normal and dry eyes we find a statistically significant difference both in goblet cell density and grade of metaplasia, between superior and temporal bulbar conjunctiva. The differences in grade of metaplasia and goblet cell density between normal and dry eyes are significant in the superior conjunctiva, but in the temporal conjunctiva we only find significant differences in grade of metaplasia.